(1) Field of the Invention
The present invention relates to an NMR spectrometer which has split-pair magnets and a bore having multi axes and, in particular, to positioning of an NMR probe and a room temperature shim coil.
(2) Description of Related Art
In recent years, sensitizing of the NMR spectrometer has been improved so that even for a protein having a complicated molecular structure or the like, structural analysis can be performed by using an NMR signal. As methods for sensitizing of the NMR spectrometer, a method of strengthening the magnetic field strength in a uniform magnetic field space in which a measuring specimen is placed and a method of varying the shape of a probe coil, are known. In the former method, a superconducting wire material is used for a magnet generating the magnetic field, and the sensitization is achieved by improving the properties of the magnet. In the latter method, by changing the shape of the NMR spectrometer from a conventional saddle shape or birdcage shape to a solenoid shape, the detection efficiency of the NMR signal is improved by a shape effect, and improvement of the sensitivity of the NMR spectrometer can be expected.
However, in order to measure the NMR signal using a solenoid probe coil, the axial direction of the probe coil and the direction of the uniform magnetic field space have to be perpendicular to each other. But, this is very difficult to be achieved, because if insertion of a sample tube in the probe coil is also considered, the direction of the uniform magnetic field and the direction in which the sample tube is inserted are coaxial with each other in the NMR spectrometer using the solenoid magnet.
In order to measure the NMR signal in high sensitivity without depending on the configuration of a superconducting magnet and the shape of the probe coil, it is important to accurately install the probe coil and the sample tube in a uniform magnetic field space made by the superconducting magnet and a shim coil for controlling the magnetic field. An NMR spectrometer using a solenoid magnet includes a room temperature space in the vertical direction being substantially equal to the axial direction of the magnet, and has a configuration in which an NMR probe and the sample tube are installed by being inserted from below and above the room temperature space, respectively. Therefore, a method has been considered, in which the sample tube is installed to an accurate position in the axial direction by the shape of a spinner attached to the sample tube and device tools, and the NMR probe is installed to a substantially same position even if it is exchanged or took out and put number of times. Examples with respect to the technology are disclosed in JP-A-2000-292515 and JP-A-2002-311118.